Dimethyl acetylenedicarboxylate → Pyrrolo(1,2-b)isoquinoline-1,2-dicarboxylic acid, 5,10-dihydro-3-methyl-, dimethyl ester

HRID 1958526Notes

Reaction equation

[C:1]([N:4]1[CH:13](C(O)=O)[CH2:12][C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH2:5]1)(=O)[CH3:2].[C:17]([C:23]([O:25][CH3:26])=[O:24])#[C:18][C:19]([O:21][CH3:22])=[O:20]>C(OC(=O)C)(=O)C>[CH3:22][O:21][C:19]([C:18]1[C:17]([C:23]([O:25][CH3:26])=[O:24])=[C:1]([CH3:2])[N:4]2[C:13]=1[CH2:12][C:11]1[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=1[CH2:5]2)=[O:20]

Participants

Conditions

Temperature: 65 °C

Procedure

A mixture of 2-acetyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (6.22 g, 20 mmol) and dimethyl acetylenedicarboxylate (4.26 g, 30 mmol) in acetic anhydride (50 mL) was heated at 60-70° C. for 3.5 hours. The reaction mixture was then cooled to room temperature and then evaporated under reduced pressure to dryness. The solid residue was recrystallized from ethanol to give 3-methyl-5,10-dihydropyrrolo[1,2-b]isoquinoline-1,2-dicarboxylic acid dimethyl ester 7.38 g, (94.4%); mp 155-158° C.; 1H NMR (DMSO-d6) δ δ 3.70 (3H, s, OMe), 3.86 (3H, s, COOMe), 3.89 (3H, s, COOMe), 4.41 (2H, s, CH2), 4.86 (2H, s, CH2), 7.01 (2H, d, J=8.5 Hz, ArH), 7.12 (1H, m, ArH), 7.22-7.25 (1H, m, ArH), 7.30-7.32 (1H, m, ArH), 7.37 (2H, d, J=8.5 Hz, ArH), 7.37-7.38 (1H, m, ArH); m/z 391.0 (M+H)+ Anal. Calcld. for C23H21NO5. 0.1H2O: C, 70.25; H, 5.43; N, 3.56. Found: C, 70.15; H, 5.44; N, 3.49.

Workup

temperatureThe reaction mixture was then cooled to room temperature
customevaporated under reduced pressure to dryness
customThe solid residue was recrystallized from ethanol

Sources & evidence

ORD record: ord-5bf9df2f50114cd7aed87d3864986d75
Source dataset: uspto-grants-2013_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08410130B2

Reaction notes

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